Implantable therapy leads may be configured for active fixation. A common arrangement for a lead configured for active fixation provides a lead distal end with an active fixation helix that extends from the distal end of the lead when a contact pin is rotated at a proximal end of the lead. As the contact pin is rotated about its longitudinal axis, the sharp helix rotates and extends from the lead distal end to screw into myocardial tissue. In some other embodiments, a stylet or other tool is inserted through the lead body to deploy the active fixation helix via rotation and/or sliding distal displacement of the active fixation helix brought about by complementary interaction of the stylet or other tool with structural features of, or associated with, the active fixation helix.
Active fixation implantable therapy leads typically have an inner lumen running from the proximal end of the lead to the distal end of the lead. This lumen is open on both ends of the lead and blood from patients can leak into the lead during implant. Although this blood leakage does not impact the ability of the lead to deliver therapy, blood coagulating inside the lumen can cause difficulty with respect to inserting a stylet into the lead and extending or retracting the helix, all of which can make lead implanting or explanting more difficult.
Complicating any solution to blood leaking into the inner lumen includes the need for the solution to not have an excessive impact on the ability of the helix to extend and retract. Accordingly, there is a need in the art for an active fixation lead that addresses these concerns.